Species 8-12 (2 in the flora): c and se United States, Mexico, West Indies, Central America, South America, tropical, subtropical, and warm-temperate regions of the Old World.

The groups of plants referred to as Achyranthes and Alternanthera have been subject to considerable nomenclatural confusion, primarily because P. C. Standley (1915) designated Achyranthesrepens Linnaeus as the lectotype species of Achyranthes. As a result, species that had been placed in Achyranthes were transferred to Centrostachys Wallich, and species that had been in Alternanthera were transferred to Achyranthes. A. A. Bullock (1957; see also R. Melville 1958) showed that Standley’s lectotypification was incorrect and that the type species of Achyranthes is Achyranthes aspera Linnaeus. The generic concepts of Achyranthes and Alternanthera then returned to those prior to 1915.